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Submitted to: National Conference on Urban Entomology
Publication Type: Proceedings Publication Acceptance Date: 9/14/2016 Publication Date: 8/22/2017 Citation: Oi, D.H. 2017. Bait development for Tawny Crazy Ants. National Conference on Urban Entomology. pg 57. Interpretive Summary: Abstract only Technical Abstract: The tawny crazy ant, Nylanderia fulva, is an invasive ant from South America that is spreading in the southern USA. As of December 2015, N. fulva was reported from at least 85 counties or parishes primarily among all the gulf coast states. In addition this ant is found on St Croix in the U.S Virgin Islands. Control of N. fulva is challenging and effective baits and bait application methods are needed. Preliminary laboratory tests and field applications of dinotefuran bait formulations have shown efficacy against N. fulva as well as another invasive, the yellow crazy ant, Anapolepis gracilipes. To further characterize the efficacy of dinotefuran bait on N. fulva, delayed toxicity profiles and efficacy against colonies were determined for a range of concentrations. To generate delayed toxicity profiles, 12 replicates of 50 N. fulva workers were given access to liquid bait formulations of 25% sucrose solution (w/v) with dinotefuran concentrations of 0.25%, 0.05%, 0.005%, 0.0005%, 0.00025%, 0.00005%, or 0% (control). Percent cumulative mortality was determined at 1, 2, 4, 6, 8, 12, 24, 48, 72 hours and on 6, 8, 10, 13, and 14 days after baits introductions. Exposure to the highest and lowest concentrations of dinotefuran (0.25% & 0.00005%) had less than 90% cumulative mortality by the end of the study. The remaining concentrations had mortalities of 90 to 95%. However, none of the baits met Stringer’s standard criteria for effective ant bait active ingredients for fire ants: <15% mortality after 24 hours and =90% mortality within 14 days. All of the concentrations had >50% mortality at 24 hours. Nylanderia fulva colony efficacy (n=4) was evaluated for a 1000-fold range of dinotefuran concentrations (0.25%, 0.05%, 0.005%, 0.0005%, & 0.00025%) in 25% (w/v) sucrose solution. Colonies were starved for 24 hours, then provided bait access for 24 more hours. All bait formulations caused significant reductions in live workers (>90%) relative to the control. Brood volume was also significantly lower than the controls in all but the lowest dinotefuran concentration (0.00025%). In the three highest concentrations, all queens (10 queens/colony) died; while 1-4 queens per colony survived in the two lower concentrations (0.0005%, & 0.00025%). While the Stringer bait criteria for delayed toxicity was not met, the dinotefuran formulation was effective against laboratory colonies of N. fulva over a broad dose range of at least 100-fold. |
